A highly functional component requires design and manufacturing techniques which can cope not only with the size and cost reduction of the product but also with the product diversification and the reduction in product cycle time. Also, in the MEMS technique which provides highly functional components and which is expected as a driving force of new industry, techniques for higher integration and higher functionality have been required. At the same time, in the stage of practical application, it has also become important to solve problems, such as reduction in the manufacturing cost and production time in a small amount and many kinds of products.
Further, in order to practically use such MEMS component as an actual product, unlike the case where a semiconductor chip is used, it is generally required to integrate the MEMS component into the product with high reliability without deteriorating the sensor and actuator functions of the component. It is found that the cost of the mounting technique used to implement such integration occupies a substantial part of the MEMS device cost.
Particularly, in such fields as medical care and welfare services, for a MEMS component (human device) required to adopt human interface, a robot, and an on-vehicle device, it is necessary to significantly reduce the mounting cost, and to significantly improve mounting flexibility to cope with design and specification changes and with the custom-made and add-on-made designs. Thus, a high-speed and fine patterning technique for electronic materials has become important.
However, in the case where a film, which is formed by applying etching, or the like, to a thin film that is made of a metal or non-metal material and that is masked by a photolithography process, is finely patterned, there are a number of manufacturing problems such as that the patterning process becomes complicated, that the flexibility of the pattern is also greatly limited and thereby it is difficult to form a continuous pattern in an area having a large level difference, and that, in the case where the non-metal material is finely patterned, since the etching speed is slow and the etching temperature is high, there are many manufacturing problems such that the etching gas causes damage to the substrate as well as the device structure and also causes deterioration in the durability of the mask material, and the like.
Thus, in recent years, a method has been proposed, by which, without using the etching process, a fine pattern of a metal or ceramic film is formed in such a manner that a raw material, such as metal nanoparticle ink and a metal alkoxide solution, is formed into liquid droplets by an inkjet method, that a fine pattern is formed by being directly drawn on a substrate, and that the formed fine pattern is then subjected to heat treatment, or the like. A pattern having a line width of about 1 μm has also been able to be formed by micronizing the liquid droplet.
In the case of this method, the fine pattern formed on the substrate is not crystallized or metallized before the heat treatment, and hence the functions of the pattern are not exhibited when the pattern is left as it is.
Thus, the fine pattern is subjected to the heat treatment so as to be crystallized. However, this method has problems that it is difficult to stably produce devices because, when many films are subjected to the heat treatment at once after being stacked in layers, the films shrink due to the crystallization of the films and thereby crack and exfoliation are caused, and that, in order to obtain a thick film, it is necessary to deposit the film on the same place many times and hence a thick film pattern is difficult to be formed at high speed.
In the conventional ink jet method, it is not possible to perform fine drawing because, when the liquid droplet is made to impact on the substrate, the liquid droplet is spread due to the wettability based on the surface tension of the liquid droplet on the substrate material, and due to the capillary effect based on the surface roughness of the substrate, so as to cause the line width to become several times or more of the liquid droplet diameter. In order to cope with such problems, the development directed to the fine drawing has been made generally in such a manner that various kinds of surface treatment are applied to the substrate surface so as to control the wettability and suppress the spread of the liquid droplet.
Further, a fine ink jet technique has been developed, in which fine drawing with a line width in the order of micrometers can be realized in such a manner that the size of the nozzle opening is reduced to 10 μm or less and that the volume size of discharged liquid droplets is reduced to 1/1000 or less by using the electric field suction (see, for example, Patent Document 1). According to Patent Document 1, drawing with a line width of several micrometers can be realized in such a manner that the evaporation rate of the solution is nonlinearly increased by reducing the liquid droplet size, and that the spread of the liquid droplet is thereby reduced after the impact of the liquid droplet on the substrate.
Patent Document 1: JP 2004-165587 A